Various types of foam products, such as automotive headrests and armrests, may be fabricated on multiple station foam injection machines. One type of foam injection machine employs a foam head and an indexing carousel containing up to 36 tools having predefined cavity shapes and controllable components for accepting a predetermined amount of a selected foam from the foam head, and maintaining the foam under pressure within the tool cavity until it cures into a desired shape.
In one multiple station foam injection molding process, referred to as "foam-in-place", a component cover, typically made of suitable cloth, vinyl, or leather, is placed in the cavity in each of the tools, and the foam is injected into the envelope defined by the cover within the tool. The foam then cures inside the cover, and the covered, foamed product is removed from the tool.
Multiple station foam injection machines typically employ a central controller, such as a programmable logic controller (PLC), which monitors the position of each of the tools on the indexing carousel, monitors a set of preselected conditions for each of the tools, and transmits control signals, as needed, to operate a predefined number of controllable components in each tool before and after foam injection, as well as to initiate the foam pour when appropriate for each tool.
The central PLC is programmed to monitor a specific standard set of conditions, and to transmit control signals to initiate a standard set of actuable component operations on each of the up to 36 tools on the carousel.
It is occasionally desirable to include at least one tool in a multiple station carousel which is nonstandard (i.e., it has a different number and/or type of actuable components, different component movements, different timing, or other different process requirements), such as a tool for a prototype or limited production part. It is normally impractical to reprogram the PLC to expand the capability of a specific nonstandard tool without wiring changes or complex programming changes.